Biopsy samples have been obtained in a variety of ways in various medical procedures using a variety of devices. Biopsy devices may be used under stereotactic guidance, ultrasound guidance, MRI guidance, PEM guidance, BSGI guidance, or otherwise. For instance, some biopsy devices may be fully operable by a user using a single hand, and with a single insertion, to capture one or more biopsy samples from a patient. In addition, some biopsy devices may be tethered to a vacuum module and/or control module, such as for communication of fluids (e.g., pressurized air, saline, atmospheric air, vacuum, etc.), for communication of power, and/or for communication of commands and the like. Other biopsy devices may be fully or at least partially operable without being tethered or otherwise connected with another device.
Merely exemplary biopsy devices are disclosed in U.S. Pat. No. 5,526,822, entitled “Method and Apparatus for Automated Biopsy and Collection of Soft Tissue,” issued Jun. 18, 1996; U.S. Pat. No. 6,086,544, entitled “Control Apparatus for an Automated Surgical Biopsy Device,” issued Jul. 11, 2000; U.S. Pub. No. 2003/0109803, entitled “MRI Compatible Surgical Biopsy Device,” published Jun. 12, 2003; U.S. Pub. No. 2006/0074345, entitled “Biopsy Apparatus and Method,” published Apr. 6, 2006; U.S. Pub. No. 2007/0118048, entitled “Remote Thumbwheel for a Surgical Biopsy Device,” published May 24, 2007; U.S. Pub. No. 2008/0214955, entitled “Presentation of Biopsy Sample by Biopsy Device,” published Sep. 4, 2008; U.S. Pub. No. 2009/0171242, entitled “Clutch and Valving System for Tetherless Biopsy Device,” published Jul. 2, 2009; U.S. patent application Ser. No. 12/335,578, entitled “Hand Actuated Tetherless Biopsy Device with Pistol Grip,” filed Dec. 16, 2008; U.S. patent application Ser. No. 12/337,942, entitled “Biopsy Device with Central Thumbwheel,” filed Dec. 18, 2008; and U.S. patent application Ser. No. 12/483,305, entitled “Tetherless Biopsy Device with Reusable Portion,” filed Jun. 12, 2009. The disclosure of each of the above-cited U.S. Patents, U.S. Patent Application Publications, and U.S. Patent Applications is incorporated by reference herein.
In some settings, including some of those where a biopsy device tip needs to penetrate the tissue of a patient, some users of biopsy devices may prefer that the tip penetrate tissue with relatively little force. In other words, in some settings, a user may prefer a first biopsy device over a second biopsy device due to the first biopsy device requiring less force for its tip to penetrate tissue than the force required for the tip of the second biopsy device to penetrate tissue. This preference may be heightened when the tissue is relatively dense or under other circumstances. This preference may also be present in settings where the biopsy device tip is inserted in tissue by hand (e.g., rather than using a firing mechanism, etc.).
Some biopsy devices may have a needle portion that has a generally circular cross-section, a generally ovular cross-section, a generally elliptical cross-section, a “figure eight” type of cross section, or some other cross-section. Such needle portions may have a predefined outer perimeter about a longitudinal axis. In some settings, the ratio of the length of an incision in tissue to the length of the perimeter or circumference of a biopsy device needle may be indicative of the magnitude of the force required to push the needle into dense tissue. For instance, in some settings, a relatively higher ratio of incision length to outer perimeter length may yield rises in tissue dilation hoop stresses that are more ideal (e.g., lower rates of rise) than rises in tissue dilation hoop stresses obtained using a relatively lower ratio of incision length to outer perimeter length (e.g., higher rates of rise).
While several systems and methods have been made and used for obtaining a biopsy sample, it is believed that no one prior to the inventors has made or used the invention described in the appended claims.